Fuel burner

ABSTRACT

An improved burner apparatus including a plurality of conduits discharging a gaseous fuel along an outwardly divergent path and the means for changing the location of said path.

United States Patent [191 Krippene et al.

[ Sept. 10, 1974 FUEL BURNER Inventors: Brett C. Krippene; Merle M. Clark,

both of Barberton; Apostol Triffon, Stow, all of Ohio The Babcock & Wilcox Company, New York, NY.

Filed: Mar. 22, 1973 App]. No.: 343,984

Assignee:

US. Cl. 431/279, 110/22 A, 431/8, 431/175 Int. Cl F23c 5/10, F23g 9/00 Field of Search 431/8, 174, 175, 176, 177, 431/178, 278, 279; 110/22 A, 28 A, 28 R References Cited UNITED STATES PATENTS 11/1949 Zink ..43l/174X 2,672,191 3/1954 Campbell et a1 431/178 2,782,738 2/1957 Zoller 3,076,496 2/1963 Rackley et a1.

3,115,851 12/1963 Ceely 110/28 R Primary Examiner-John J. Camby Attorney, Agent, or Firm-Joseph M. Maguire, Esq.; Robert J. Edwards, Esq.

[57] ABSTRACT An improved burner apparatus including a plurality of conduits discharging a gaseous fuel along an outwardly divergent path and the means for changing the location of said path.

9 Claims, 6 Drawing Figures PATENIE SE? 1 0 I914 saw 1 or 2 FUEL BURNER BACKGROUND OF THE INVENTION The present invention relates to a fuel-burning apparatus, and, more particularly, to an improved gaseous fuel burner to be fired along or in combination with a liquid fuel burner.

Heretofore, manufacturers of gaseous fuel-burning equipment have had to contend with the special problem of avoiding furnace and setting vibration resulting from ignition instability of the burners. This problem is particularly arcute on larger units which, by virtue of their size, may have nearly an acre of flat boiler casing designed to relatively low static pressures that are subject to possible harmonious vibrations with the combustion process. Such vibrations may start from ignition instability of a single gas conduit on one burner which may then lead others to vibrate and eventually set up a harmonious and destructive vibration of the furnace enclosure.

To offset the tendency for burner vibrations, the gaseous burner conduits must be capable of operation with stable ignition over a wide range of fuel rates and burner velocities.

SUMMARY OF THE INVENTION The present invention avoids random vibrations that may cascade into serious furnace vibrations by providing an arrangement wherein the individual gas conduits are axially and radially adjustable with respect to the burner port and to associated flame retainers to orient the conduit discharge orifices to result in somewhat random patterns and thereby minimize harmonious cascading of vibrations from one conduit or one burner to another.

It has been found that where the initial point of flame ignition can be maintained at the flame retainers as the primary source, the ignition and burning process has the best characteristics of stability and continuous combustion and is relatively free from noise and vibration.

It has been further determined that each step forward which the point of initial ignition takes along the path of the flame results in the loss of a degree of stability, thereby increasing the potential for noise and vibration. Moreover, the greatest potential for burner noise and vibration occurs when the source of initial ignition shifts back and forth from one point to another.

It has also been determined that some degree of asymmetry between gas elements in a burner and between burners is often required to minimize harmonious cascading of vibrations.

In accordance with the invention, there is provided an improved fuel burning apparatus, a portion thereof being disposed within a windbox to which combustion air is supplied and which is formed between adjacently disposed burner and furnace walls of a vapor generating unit. The burner wall is formed with an access opening for admitting that portion of the fuel burning apparatus which normally resides in the windbox whereas the furnace wall is formed with a burner throat which accommodates the combining of fuel and air into a combustible mixture and the ignition thereof. The fuel burning apparatus includes a gaseous fuel burner comprising a plurality of conduits concentrically disposed about the central axis of the burner and having 2 their respective outlet ends terminating within the periphery of the burner throat and their inlet ends disposed outside of the windbox. The outlet end of each conduit is provided with one or more orifices formed in the wall portion thereof to discharge gaseous fuel in an outwardly divergent path with respect to the central axis of the conduit. A separate guide tube is associated with each of the conduits, the guide tube being fitted with a flame retainer which cooperates with the conduit outlet end to maintain stable flame ignition. The

inlet end of each conduit includes a threaded portion which engages a stationary cap and provides the means for rotating the conduit thereby allowing a rotative and linear shifting of the position of the orifices with respect to the central axis of the conduit with the concomitant effect of changing the location of the gaseous fuel discharge path.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation including the fuel burning apparatus embodying the invention.

FIG. 2 is a rear end view of FIG. 1.

FIG. 3 is a schematic showing of .a selected front end position of the gas burner conduits.

FIG. 4 is a detail and fragmented partially sectional side view of one of the gas burner conduits fixed in its rearmost position.

FIG. 5 is a detail sectional view of the inlet end of one of the gas burner conduits when fixed in its foremost position.

FIG. 6 is a detail end view of one of the gas burner conduits.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In the illustrated embodiment disclosed in the drawings, the burner assembly is shown as adapted for a fuel burning apparatus having a gaseous and liquid fuel burner and applied to a furnace having a refractory wall formed with a burner throat. It willbe understood, however, that the invention is equally applicable to fuel burning apparatus having only a gaseous fuel burner.

Referring to FIG. 1, reference numeral 10 is directed at a fuel burning apparatus which is arranged to fire through a circular port 12 formed in a refractory lined front wall 14 of a furnace chamber (not shown). A burner wall 16 having an axis port 18 is spaced from the furnace front wall 14. The space between the burner and front walls forms a windbox or passageway 20 to which combustion air is supplied from a suitably controlled source (not shown). The circular port 12 is lined with a throat 22 which is formed of a short cylindrical section 24 connected at its discharge edge with a flaring section 26 and at its inlet edge with the smaller diameter end of a frustoconical section 28. The sections of burner throat 22 are formed of suitable refractory material. The fuel burning apparatus 10 includes a cylindrical register assembly 30 which is located within the windbox 20 and is suitably supported therefrom and arranged to receive the combustion air for discharge through the burner throat 22.

The register assembly 30 includes a front annular plate 32 and a back circular plate 34. The front and back plates are spacedfrom one another to accommodate a plurality of circumferentially arranged plates or vanes 36 pivotally mounted therebetween so as to be rotatable about their respective axis, each of which is substantially parallel with the central axis of the port 12. Although no register operating devices are shown in the drawings, it will be appreciated that there are known devices operable from without the windbox 20 for simultaneously pivoting the register vanes 36 about their respective axis.

The improved gas burner arrangement 38 of the present invention includes an annular gaseous fuel manifold 40 disposed within windbox 20 in a plane substantially parallel to the burner port 12 and spaced therefrom and adjacent to the cover plate 42, the latter being bolted to the burner wall 16 and acting as a closure for access port 18. The manifold 40 is connected to a supply pipe 43 and receives therefrom a controlled quantity of pressurized gaseous fuel. Circumferentially spaced about a peripheral portion of the gas manifold 40, there are provided a plurality of nipples 44, each having one end flow connected to the gas manifold 40 and the other end extending through a support sleeve 46. The latter end of each of the nipples 44 is releasably flow connected to a corresponding gas conduit cap 48 which is in turn threadably engaged with the inlet end of a respective gaseous fuel conduit or element 50. A locknut 52 threads onto the inlet end of the conduit 50 to fixedly secure the latter in a selected radial and axial position. A plurality of guide tubes 54 are equidistantly spaced about the manifold 40 and concentrically disposed about a longitudinal axis of the burning apparatus 10, each guide tube 54 extends through a corresponding support sleeve 46 and through spaced openings 56 of the cover plate 42, and projects inwardly through the windbox and register assembly toward the burner port 12. The distal end of each guide tube 54 has connected thereto a flame retainer 58. Each gaseous fuel conduit 50 is slidably disposed within a respective guide tube 54 with its discharge end protruding a short distance beyond the open end of the flame retainer 58.

In the embodiment shown, a liquid fuel burner 60 is used in combination with the gas burner 38 as part of the fuel burning apparatus 10. The liquid fuel burner 60 comprises a guide tube or distance piece 62 extending along the central axis of the burner assembly and supported in a sleeve 64, the latter extending through an opening in the cover plate 42. The distance piece 62 has one end threadably engaged with a yoke assembly 66, the latter being connected to the liquid fuel and atomizing vapor lines (not shown). The discharge end of yoke 66 is connected to an atomizer assembly 68 for the through passage of fuel and atomizing vapor. A leak-proof fit between the yoke 66 and the atomizer 68 is achieved by introducing a gasket (not shown) between the mating surfaces and applying pressure with a locking device 70. A barrel tube 72 is connected at its inlet end to the atomizer assembly 68 and at its outlet end to a sprayer plate (not shown), the tube 72 extends through the distance piece and out the distal end thereof. The distal end of distance piece 62 includes a support ring 74 and an end deflector 76 attached thereto. The deflector 76 is in the shape of a truncated cone and is concentrically disposed about the longitudinal axis of the burner throat 12 and includes a central opening to accommodate the passage therethrough of the sprayer plate end of the barrel tube 72.

Referring to FIGS. 2 and 3, there are illustrated respectively the rear end view of the fuel burning apparatus 10 showing the circular cover plate 42 including an observation port 78, and a schematic view of the discharge end of the elements 50 in a selected position corresponding to that of FIG. 2. The liquid fuel burner atomizer 68 is shown encircled by eight gaseous fuel conduits 50 with their respective inlet ends protruding from the cover plate 42, each extending through respective caps 48 and being equispaced from the liquid fuel burner and from each other and having an end face etched to indicate the position of the discharge orifice 80 at the distal end of the element 50 as shown at FIG. 3. It will be understood that the position of the discharge orifices 80 herein shown, depicts only one of mamy gaseous fuel discharge patterns which are obtainable with the present invention. As will be shown in the detail figures which follow, each gaseous fuel conduit 50 is adjustable in both radial and axial direction to provide the appropriate firing pattern for a given operating mode.

Referring to FIG. 4, there is shown a detail sectional side view of one of the gas burner conduits 50 fixed in its rearmost position and including the guide tube 54 with the outlet end connected to the flame retainer 58 and the inlet end abutting the gas element cap 48. The retainer 58 is in the form of an open ended cylinder having an annular base portion 82 whose inner periphery fits over the distal end of the guide tube 54 and is threadably or weldably attached thereto. The side portion 84 extends a short distance beyond the distal end of tube 54 and is radially spaced from and concentric with the gas burner conduit 50. The flame retainer 58 acts as a shield which protects the gaseous fuel ignition zone from indiscriminate flow of combustion air while allowing sufficient air to sustain the combustion process. The air is admitted into the flame retainer 58 through a plurality of orifices 86 and 88 which are located at the base and side portions 82 and 84, respec-' tively. The orifices 86 (four in the embodiment) extend in a direction parallel to the longitudinal axis of the flame container 58 while the orifices 88 (eight in the embodiment) extend radially thereto. It will be understood that the number and sizing of orifices will vary in accordance with the requirements of the particular installation. The inlet end of guide tube 54 abuts cap 48 by extending into a recessed portion 91 of the cap, the latter being fitted with a ring-type gasket which cooperates with the end of the guide tube to form a gastight seal therebetween. The guide tube 54 extends through the support sleeve 46 and is weldably fixed thereto.

The gas conduit cap 48 is formed with an internal passageway having three openings 94, 96, and 98, the former two being coaxially aligned. Opening 94 includes the recessed portion 91 which houses the gasket 90 and a circumferential trough which houses an O-ring 102. Opening 96 includes a threaded portion 106 and circumferential trough 108 which houses an O-ring 110. Opening 98 includes a recessed portion 112 which is fitted with a ring-type gasket 114, the latter cooperates with the end of the nipple 44 which abuts thereto to form the gastight seal therebetween. The nipple 44 extends through the support sleeve 46 and is weldably fixed thereto.

The gas burner conduit 50 is formed of an elongated pipe member having a discharge end including two converging angular end faces 83. The embodiment shown has three large diameter orifices 80, one of which is located on one of the angular end faces 83 while the remaining two are located at diametrically opposite points of the conduit portion lying between the angular end faces. Eight smaller diameter orifices 81 are equidistantly spaced about the circumference of the conduit immediately upstream gas flow-wise of the angular end faces. It would be appreciated that the angular configuration of the conduit discharge end as well as the relative size and number of orifices will vary in accordance with the requirements of the particular installation. The elongated conduit 50 has a capped inlet end including an end face protusion 116 having two opposed arcuate sides concentric with the central axis of the conduit 50 and two opposed flat sides lying along respective planes which are parallel to the leading edges formed by the respective angular end faces 83. A threaded portion 118 is formed over the outer periphery of conduit 50 and extends along a segment of its length adjacent to the inlet face. Gaseous fuel is admitted to the conduit 50 through a plurality of ports 120 extending through the wall of the conduit inlet end and intermediate of the threaded portion 118 and the discharge end of the conduit. The preferred embodiment includes four ports of equal size and equiarcuately spaced about the circumference of conduit 50. The ports 120 are arranged in pairs which are normal to one another and are spaced the distance of a port radius from each other along the central axis of the conduit. It will be understood that the number and sizing of intake ports will vary in accordance with the requirements of the particular installation. The inlet end of the conduit 50 cooperates with the O-rings 102 and 110 to form a gastight seal at the openings 94 and 96, respectively. The locknut 52 is threadably engaged with portion 118 to secure the conduit 50 in the selected axial and radial position.

Referring to FIGS. 5 and 6, there are shown respectively a detailed sectional view of the inlet end of one of the gas burner elements 50 fixed in its foremost position and a detailed end view thereof, including guide tube 54 abutting the gas conduit cap 48, the latter being bolted to the support sleeve 46 through a pair of locking bolts 125.

The internal passageway 92 extending through the cap 48 includes the threaded portion 106 which cooperates with a like threaded portion 118 of the conduit 50 to permit radial and axial adjustment of the conduit 50 within prescribed limits. In the preferred embodiment the head or protruding portion 116 of conduit 50 is etched on its end face with guide marks 124 which correspond to respective radial positions of the gas discharge orifices 80. The adjustment of conduit 50 is effected by placing a wrench (not shown) on the protruding portion 116 and rotating it in a clockwise or counter-clockwise direction while using the guide marks 124 as an indication of the radial position of discharge orifices 80 and using the threaded portion 118 as an in dication of the axial position of the orifices 80 with respect to the flame retainer 58, as well as the port 12. When the conduit 50 has been located in the desired axial and radial position, a wrench (not shown) is applied to lock nut 52 to fixedly secure the conduit 50 against the cap 48. It will be appreciated that there are known devices for mechanically adjusting and securing the conduit 50in the desired position.

It will be understood that the allowable range of axial adjustment is governed by the length of the threaded portion 118 which, in turn, is predicated on the depth of passageway 92 as related to the size and number of intake ports 120. In the preferred embodiment, for example, the maximum forward axial adjustment for conduit 50 is equivalent to the distance taken along its central axis between the leading circumferential edge of the foremost intake port and the inner surface of front wall 122 of cap 48 adjoining the periphery of opening 94. The maximum rearward axial adjustment is equivalent to the distance taken along the conduit central axis between the trailing circumferential edge of the rearmost intake port and the inner surface of rear wall 123 of cap 48 adjoining the periphery of opening 96. A forward stop is provided by establishing an axial length for the threaded portion 118 which has the trailing end face of threaded portion 118 lying flush with the trail ing end face of locknut 52 when the conduit 50 is in its foremost or maximum inserted position. A rearward stop is provided by shoulder portions 126 which abut against the respective front peripheral edges of openings 94 and 96 when the conduit 50 is in its rearmost or maximum retracted position.

In the operation of the preferred embodiment, pressurized gaseous fuel is conveyed to the burner through a supply pipe 43 to the manifold 40 whence it is equally distributed through eight nipples 44, each of which is flowconnected to a corresponding; cap 48 which in turn communicates with a respective conduit 50 to pass gaseous fuel therethrough for discharge through the port 12 along an outwardly divergent path in the presence of combustion air. Each conduit may be individually adjusted during the operation of the burner, from the operating platform, to change the radial and axial posi' tions of the discharge orifices and 81' with respect to the burner throat 22 and the corresponding flame retainer 58, thereby causing a change in the location of the gaseous fuel path.

One of the many advantages to be derived from the present invention is the ability to achieve and maintain stable ignition at each conduit by changing the axial and/or radial position of the discharge orifices with respect to the corresponding flame retainer. Among the manifold benefits arising out of ignition stability at the individual burner conduits are a higher efficiency resulting from lower carbon loss, a prevention or attenuation of combustion induced vibration, and a lower peak flame temperature throughout the operating range with the concomitant effect of inhibiting the formation of oxides of nitrogen. Another advantage to be derived from the present invention is the ability to introduce a degree of asymmetry between fuel discharge paths of different conduits or burners thereby minimizing harmonious cascading of vibrations.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

1. In combination with a first wall having at least one burner port extending therethrough, a second wall spaced from the first wall and forming a passageway therewith for flow of combustion air to the port, an improved burner apparatus and means for supplyingpressurized gaseous fuel thereto, said apparatus having a portion thereof disposed within the passageway and including at least one conduit having an inlet and an outlet end, said outlet end being disposed adjacent the port and being formed with at least one discharge orifice directing the gaseous fuel along a path offset from the central axis of the conduit, and said inlet end including means for changing the location of said gaseous fuel discharge path, the last name means comprising a threaded portion formed along the outer periphery of said inlet end.

2. The combination according to claim 1 wherein said inlet has a closed end face and includes at least one opening through its side wall for admitting gaseous fuel to said conduit.

3. The combination according to claim 2 including a cap having a passageway communicating with said opening, the cap being formed with a sleeve-like segment for receiving said inlet end.

4. The combination according to claim 3 including a threaded portion formed along the inner periphery of said sleeve segment, said first and second named threaded portions cooperating with one another to permit changing the location of said gaseous fuel discharge path.

5. The combination according to claim 3 including means engaging the threaded inlet end portion to fixedly secure the conduit to said cap thereby maintaining the gaseous fuel discharge path in the selected position.

6. The combination according to claim 1 including a guide tube, said conduit having an intermediate portion thereof slidably inserted within said guide tube.

7. The combination according to claim 6 including flame retaining means connected to the distal end of said guide tube.

8. The combination according to claim 7 wherein said flame retaining means is perforated.

9. The combination according to claim 1 wherein said inlet end includes means for determining the location of said gaseous fuel discharge path. 

1. In combination with a first wall having at least one burner port extending therethrough, a second wall spaced from the first wall and forming a passageway therewith for flow of combustion air to the port, an improved burner apparatus and means for supplying pressurized gaseous fuel thereto, said apparatus having a portion thereof disposed within the passageway and including at least one conduit having an inlet and an outlet end, said outlet end being disposed adjacent the port and being formed with at least one discharge orifice directing the gaseous fuel along a path offset from the central axis of the conduit, and said inlet end including means for changing the location of said gaseous fuel discharge path, the last name means comprising a threaded portion formed along the outer periphery of said inlet end.
 2. The combination according to claim 1 wherein said inlet has a closed end face and includes at least one opening through its side wall for admitting gaseous fuel to said conduit.
 3. The combination according to claim 2 including a cap having a passageway communicating with said opening, the cap being formed with a sleeve-like segment for receiving said inlet end.
 4. The combination according to claim 3 including a threaded portion formed along the inner periphery of said sleeve segment, said first and second named threaded portions cooperating with one another to permit changing the location of said gaseous fuel discharge path.
 5. The combination according to claim 3 including means engaging the threaded inlet end portion to fixedly secure the conduit to said cap thereby maintaining the gaseous fuel discharge path in the selected position.
 6. The combination according to claim 1 including a guide tube, said conduit having an intermediate portion thereof slidably inserted within said guide tube.
 7. The combination according to claim 6 including flame retaining means connected to the distal end of said guide tube.
 8. The combination according to claim 7 wherein said flame retaining means is perforated.
 9. The combination according to claim 1 wherein said inlet end includes means for determining the location of said gaseous fuel discharge path. 